The sunlight spectrum includes the ultraviolet, visible, and infrared light wavelength ranges. Various types of equipment have been developed that simulate one or more of these light frequency ranges and are used in performing various tests, for example, on humans or materials or components to determine the effect of these light wavelength ranges on humans or materials or components.
It is well known that exposure to ultraviolet radiation can cause adverse skin conditions, including skin cancers. The predominant source of the ultraviolet radiation is sunlight radiation. Various sunscreen formulations that are applied to the skin are available to reduce or eliminate the adverse effect of sunlight on humans and various equipments used in testing the effectiveness of such sunscreen formulations (i.e., the skin reactions to various ultraviolet doses) to determine the Sunscreen Protection Factor (SPF) are available.
Test apparatus of this type that is available at the present time includes an artificial light source that provides (a) a single beam of selected intensity focused upon a subject to test skin reaction to the intensity of the single beam of ultraviolet radiation, or (b) a plurality of beams of various selected intensities focused simultaneously upon a subject to test simultaneously skin reaction to the various intensities of the plurality of beams of ultraviolet radiation.
In general, the skin reaction test units that are currently available fail to satisfy a number of the requirements of the users of such units. Some fail to provide beams of radiation having the desired uniform output intensity profiles, so that often it is difficult for the user to properly quantify and qualify the test results. Some fail to provide the users of the test units with sufficient flexibility to conduct the types of tests the users would like to conduct in an easy and efficient manner that provide accurate and repeatable results.
Yet another problem with currently available skin reaction test units is the thermal discomfort that can be experienced by certain subjects during exposure that is caused by the presence of certain wavelengths in the radiation to which the subject is exposed. Despite efforts to eliminate, for example, infrared radiation from the lamp source by the inclusion, for example, of dichroic mirrors and blocking filters, the test subjects still can be exposed, under certain conditions, to an undesirable level of infrared radiation that is not eliminated from the beams of radiations to which the test subject is exposed and, thereby, be exposed to undesirable thermal discomfort.
As to test units that are available to determine the effect of sunlight on materials and components (e.g., photovoltaic cells), many are subject to the same general criticism set out above with respect to the skin reaction test units. Some fail to provide the user with test results that are properly quantified and qualified, while others lack the flexibility to conduct the types of tests the users would like to conduct in an easy and efficient manner that provide accurate results.